I bought an '05 Legacy 2.5 with 161k and a knock. Tore the engine apart and found a bad main bearing and a pretty warn rod bearing. Rebuilt the motor but never touched the pistons or cylinders. When we split the block we left the piston assemblies in. Bought an engine gasket kit from subaru and rebuilt everything else. I was very careful, at least I thought, to follow the factory manual and installed the green seals on the exhaust valves and the gray seals on the intake valves.Everything was fine on first startup where I let the engine run for about 15 minutes at idle to bring everything up to temp. Let it cool for about an hour, then started it and drove it 15 minutes to let it set over night. Started it the following morning and drove it an hour to work. No issues during any of this. Drove it back home another hour and ran a few errands last night. This morning I started it up and got a big cloud of oil smoke out the exhaust. Shut it down and checked the oil and it was about 1/4 quart low. Drove it the hour to work and never saw obvious smoke. This screams valve guide seals to me but I wanted to get some other opinions, and even ask if anyone has ever had any follies when replacing the seals or even had bad ones from the dealer.